The invention relates generally to electronic comparators and more specifically concerns comparators with noise suppression.
Whenever a model is subjected to tests in a wind tunnel, it will usually vibrate. The vibrations are cyclic and often times sinusoidal about a zero level. It is sometimes necessary to determine how many times the amplitudes of the vibrations exceeds some predetermined reference level during a fixed period of time. To do this in the past, a transducer was placed on the model to produce an electrical signal representing the vibrations. The signals representing vibrations were compared with a reference level with conventional comparator means to produce a pulse each time the signal exceeded the reference level. Whenever the signal exceeded the reference level the comparator output was triggered on and then when the signal dropped below the reference level or a different level the output of the comparator was triggered off thereby resulting in a pulse. The prior art comparators work well except when the signal is noisy: when the input signal is noisy multiple triggering occurs resulting in false counts.
It is therefore an object of this invention to provide a method and apparatus to aid in counting the number of times a noisy cyclic signal representing vibrations exceeds a predetermined reference level during a given period of time.
Another object of this invention is to provide a comparator means for producing a pulse each time a noisy cyclic signal exceeds a reference level and for eliminating any false pulses caused by the noise.
Other objects and advantages will become apparent hereinafter in the specification and drawings.